I tend to agree. But I think that's only emphasizing the point--that intangibles like 'raised performance' and the ability to not crack under the pressure of the 7 games series reveal themselves in the playoffs in a way they never could in the regular season. Goalie getting dialed in like Quick? Maybe he does his homework, is a video monster, thrives on seeing the same guys night after night? Needs emotional engagement and some hate, maybe? Justin Williams going HAM in game 7s can easily be handwaved as 'luck,' but how does it keep happening? Also that era Kings were a team that thrived on physical contact and engagement, which is obviously ramped up in the playoffs, too. Etc. I think people too easily dismiss those as 'luck' or 'getting hot.'
Obviously it's insanely hard to win in the playoffs, so you need good team construction to survive the regular season, of course, but the 'built for the playoffs' qualities DO emerge, and yes, you need a little luck sometimes too (no injuries, a bounce, etc.). Obviously hope isn't a strategy though.